Conventionally, a stopper that mechanically restricts a motion range (rotation angle range) of a joint of a robot is known (see, for example, PTL 1 through PTL 3). In PTL 2 and PTL 3, a plurality of attachment holes used for attaching the stopper are provided around the joint. By changing the attachment positions of the stopper, it is possible to change the limit angle of the joint defined by the stopper.